:root{--brand-primary:#667eea;--brand-primary-dark:#764ba2;--brand-secondary:#e2e8f0;--brand-accent:#00d4ff;--brand-background:#0f172a;--brand-card-bg:#1a202c;--brand-error:#ef4444;--brand-success:#10b981;--brand-warning:#f59e0b;--brand-font-primary:"Inter",-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,sans-serif;--brand-font-headings:"Inter",system-ui,sans-serif}*{box-sizing:border-box}body{margin:0;padding:0;font-family:var(--brand-font-primary);background:var(--brand-background);color:var(--brand-secondary);line-height:1.6}.container{max-width:1200px;margin:0 auto;padding:0 1rem}.layout-container{min-height:100vh;display:flex;flex-direction:column}.main-content{flex:1 1;display:flex;flex-direction:column}.btn{display:inline-block;padding:.75rem 1.5rem;border-radius:.5rem;font-weight:600;text-align:center;transition:all .3s ease;border:2px solid transparent;cursor:pointer;text-decoration:none}.btn-primary{background:linear-gradient(135deg,var(--brand-primary),var(--brand-primary-dark));color:white}.btn-primary:hover{transform:translateY(-2px);box-shadow:0 10px 20px rgba(102,126,234,.3)}.btn-outline{background:transparent;color:var(--brand-accent);border-color:var(--brand-accent)}.btn-outline:hover{background:var(--brand-accent);color:var(--brand-background)}h1,h2,h3,h4,h5,h6{font-family:var(--brand-font-headings);font-weight:600;line-height:1.2;margin:0 0 1rem}h1{font-size:3.5rem}h2{font-size:2.5rem}h3{font-size:1.8rem}h4{font-size:1.4rem}h5{font-size:1.1rem}h6{font-size:1rem}p{margin:0 0 1rem}a{color:var(--brand-accent);text-decoration:none;transition:color .2s ease}a:hover{color:var(--brand-primary)}.hero-section{background:linear-gradient(135deg,var(--brand-primary) 0,var(--brand-primary-dark) 100%);color:white;padding:100px 0;text-align:center}.hero-section h1{font-size:3.5rem;font-weight:700;margin:0 0 20px;text-shadow:0 2px 4px rgba(0,0,0,.3)}.hero-description{font-size:1.3rem;max-width:600px;margin:0 auto;opacity:.95;line-height:1.6}.calculators-grid{padding:80px 0;background:var(--brand-background)}.grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(350px,1fr));grid-gap:40px;gap:40px;max-width:1200px;margin:0 auto}.calculator-card{background:var(--brand-card-bg);border-radius:16px;padding:30px;box-shadow:0 10px 25px rgba(0,0,0,.1);transition:all .3s ease;border:1px solid var(--brand-secondary);text-align:center}.calculator-card:hover{transform:translateY(-8px);box-shadow:0 20px 40px rgba(102,126,234,.15)}.calculator-card h3{color:var(--brand-primary);font-size:1.5rem;margin:20px 0 15px}.calculator-card p{color:var(--brand-secondary);font-size:.95rem;line-height:1.6;margin-bottom:20px}.calculator-icon{font-size:3rem;margin-bottom:15px}.calculator-preview{background:var(--brand-background);border-radius:12px;padding:20px;margin-bottom:25px}.calc-display{background:var(--brand-card-bg);color:var(--brand-secondary);padding:15px;border-radius:8px;text-align:right;font-family:Courier New,monospace;font-size:1.1rem;margin-bottom:15px;min-height:20px;border:1px solid var(--brand-secondary)}.calc-buttons{display:grid;grid-gap:8px;gap:8px}.calc-row{display:grid;grid-template-columns:repeat(4,1fr);grid-gap:8px;gap:8px}.calc-buttons button{background:var(--brand-primary);color:white;border:none;border-radius:6px;padding:8px 4px;font-size:.85rem;cursor:pointer;transition:background .2s}.calc-buttons button:hover{background:var(--brand-primary-dark)}.calc-link{display:block;background:linear-gradient(135deg,var(--brand-primary) 0,var(--brand-primary-dark) 100%);color:white;text-decoration:none;text-align:center;padding:12px 20px;border-radius:8px;font-weight:600;transition:all .3s ease}.calc-link:hover{transform:translateY(-2px);box-shadow:0 6px 20px rgba(102,126,234,.4);color:white}.features-section{padding:80px 0;background:var(--brand-card-bg)}.features-section h2{text-align:center;color:var(--brand-primary);margin-bottom:50px}.features-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(250px,1fr));grid-gap:40px;gap:40px}.feature{text-align:center}.feature-icon{font-size:3rem;margin-bottom:20px}.feature h3{color:var(--brand-primary);margin-bottom:15px}.feature p{color:var(--brand-secondary);line-height:1.6}.newsletter-section{background:linear-gradient(135deg,var(--brand-primary) 0,var(--brand-primary-dark) 100%);color:white;padding:60px 0;text-align:center}.newsletter-form{max-width:500px;display:flex;gap:15px;margin:30px auto 0}.newsletter-input{flex:1 1;padding:15px;border:none;border-radius:8px;font-size:1rem}.newsletter-button{background:white;color:var(--brand-primary);border:none;padding:15px 30px;border-radius:8px;font-weight:600;cursor:pointer;transition:all .3s ease}.newsletter-button:hover{transform:translateY(-2px);box-shadow:0 4px 12px rgba(0,0,0,.2)}@media (max-width:768px){.hero-section h1{font-size:2.5rem}.hero-description{font-size:1.1rem}.grid{grid-template-columns:1fr;gap:30px}.newsletter-form{flex-direction:column}.calc-buttons.converter button,.calc-buttons.date button,.calc-buttons.financial button,.calc-buttons.percentage button,.calc-buttons.scientific button{font-size:.65rem;padding:6px 2px}}.text-center{text-align:center}.text-left{text-align:left}.text-right{text-align:right}.hidden-mobile{display:block}.hidden-desktop{display:none}@media (max-width:768px){.hidden-mobile{display:none}.hidden-desktop{display:block}}